Fuel Bladder Venting

[SHAMELESS]

I Have A Lola T342 With A Fuel Bladder And Would Like Some Suggestions On How To Vent It Properly And Still Use The Check Valve.

[Steve Demeter]

One thing to make sure is that the check valve is upright, not at an angle or horizontal. If it is not upright, lit can not allow air in.

I try to mount my check valve as low as possible, but with a loop of tubing going to at least the height of the top of the cell.

In ANY case, make darn sure that the end of the vent line is OUTSIDE and BELOW the chassis.

If I ever see you in person, I can explain why, but it is too embarrassing to talk about in public.

[SHAMELESS]

Thanks Steve, With Just The Checkvalve Does It Allow For Any Venting Out For Expansion?

[DaveW]

I vent mine without a check valve. The vent starts from the filler neck, which is on the top right of the cell. The vent hose then goes across the top of the cell to near the bottom of the LH side roll hoop and back along the LH trailing arm and ends outside the body. No matter what orientation the car is in, the geometry prevents fuel from coming out. I've used this method for over 30 years, and have never had a problem.

[SHAMELESS]

Thanks, That Sounds Like The Best Way To Go.

[Steve Demeter]

Great idea from Dave as usual.

Unfortunatley, my vent is at the bottom LH corner of the cell and I realized after years of not using a check valve, that if the car was on it's right side, that fuel could come out.

[BGP]

I thought the GCR stated you had to have a check valve and have the vent exit outside the bodywork.

[DaveW]

I thought the GCR stated you had to have a check valve and have the vent exit outside the bodywork.

From the GCR, section 19.4:

"Fuel cell breathers shall vent outside the car."

There is no mention of vent-line check valves anywhere in the GCR that I could find.

Edit:
There IS a requirement for filler-neck check valves in the case of fuel fillers that are attached to bodywork.

There is also a statement saying that fuel filler CAPS which contain an unchecked vent require installation of a check valve in the filler neck.